Phase Equilibria,Microstructure, and High-Temperature Strength of TiC-Added Mo-Si-B Alloys

TiC was added to Mo-Si-B alloys using a conventional Ar arc-melting technique, and the phase equilibria, microstructure evolution, and high-temperature strength at 1673 K (1400 °C) were investigated. The primary phase changed to Mo solid solution (Mo_ss), Mo₅SiB₂ (T₂), or TiC depending on the composition. Following the primary phase solidification, a Mo_ss + TiC, Mo_ss + T₂, or Mo_ss + T₂ + TiC + Mo₂C eutectic reaction took place as the secondary solidification step. In some alloys, Mo_ss + T₂ + TiC and Mo_ss + T₂ + Mo₂C eutectic reactions were present as higher-order solidification steps. After annealing at 2073 K (1800 °C) for 24 hours, Mo_ss, T₂, TiC, and Mo₂C coexisted stably with microstructural coarsening. The coarsening rate was much faster in an alloy with no TiC dispersion, suggesting that TiC has a strong pinning effect on the grain boundary and interface migration. Compression tests conducted at 1673 K (1400 °C) revealed strength properties of almost all the alloys that were better than those of the Mo-Hf-C alloy (MHC). Alloy densities were 9 g/cm³ or less, which is lighter than pure Mo and MHC (≥10 g/cm³) and competitive with Ni-base superalloys. TiC-added Mo-Si-B alloys are promising candidates for ultrahigh-temperature materials beyond Ni-base superalloys.     

Optimum design considerations for dual conductor bubble devices

A design for dual conductor, current-access bubble devices with 8-μm periods has been optimized with a numerical calculation method for bubble motion in a propagating magnetic field, generated around hole patterns in conductor layers. Magnetic bias field distributions are calculated for an oval hole chain in the conductor layers. Bubble motion equations are obtained with analytical field distribution functions approximating the calculated field distributions. Minimum drive current density Jminfor normal bubble propagation is determined by a solution to the equations. The hole shape has been optimized by the minimization of the drive power Pmin, the product of Jminand conductor resistance, which is calculated from current distributions around the hole pattern. Optimum layer thickness have also been obtained for 8-μm period bubble devices. Both registration tolerance between the two conductor layers and bubble skew effects have been studied semiquantitatively on the basis of the equations of motion. The numerical calculation method developed here is found to be a highly effective means to optimize pattern design for smaller period devices.     

Tribological Characteristics of α-Alumina in High-Temperature Water

The effects of temperature, sliding speed, and contact load on the tribological behavior of an α-alumina ceramic sliding on the same material in water were investigated in the range from room temperature to 300°C under the corresponding saturated vapor pressures. The specific wear rate increased remarkably at elevated temperatures. The primary wear mechanisms in high-temperature water are considered to be microfracture, promoted by the solution of grain boundary layers, and stress corrosion cracking. A film containing γ-alumina particulates appeared on the worn surface with increasing sliding speed and increasing contact load in 300°C water.     

Internal stenting of the hepaticojejunostomy and pancreaticojejunostomy in patients undergoing pancreatoduodenectomy to promote earlier discharge from hospital

Arterial compliance and central blood volume were evaluated in obese and nonobese patients with and without hypertension. Arterial compliance was lower in the hypertensive group, although obese subjects, regardless of their blood pressure, had higher arterial compliance. The ratio of central blood volume to total blood volume was highest in hypertensive patients, whether obese or lean, indicating increased venoconstriction.     

Two-dimensional simulation and measurement of high-performanceMOSFETs made on a very thin SOI film

Thinning effects on the device characteristics of silicon-on-insulator (SOI) MOSFETs are discussed. Two-dimensional/two-carrier device simulation revealed the following advantages. An n-channel MOSFET with 500-Å-SOI thickness exhibited a high-punchthrough resistance as well as an improved subthreshold swing down to a deep submicrometer region, even if the film was nearly intrinsic. A capacitance coupling model has been proposed to explain these subthreshold characteristics. The kink elimination effect, which was attributed to a significantly reduced hole density in the SOI film, was reproduced. The low-field channel mobility exhibited a significant increase, which was ascribed to a decrease in the vertical electric field. Moreover, the current-overshoot phenomenon associated with the switching operation was suppressed. Excess holes recombine with electrons quickly after the gate turn-on, bringing about a stabilized potential in the SOI substrate. Experiments were also carried out to verify the simulation     

Lower submicron pattern definition by high-voltage electron-beam lithography

High-voltage electron-beam writing on polymethyl methacrylate (PMMA) at 50 kV with a dose of 50 ?C/cm2 has been found to give an outstanding result of the simultaneous formation of isolated and arrayed quarter-micron window patterns of the same size as the electron-beam diameter of a quarter micron.     

Development of electroluminescence based pressure-sensitive paint system

We introduce a pressure-sensitive paint (PSP) measurement system based on an electroluminescence (EL) as a surface illumination. This consists of an inorganic EL as the illumination, a short-pass filter, and a platinum-porphyrin based PSP. The short-pass filter, which passes below 500 nm, was used to separate an overlay of the EL illumination and the PSP emission. The EL shows an opposite temperature dependency to that of the PSP. It gives a uniform illumination compared to that of a point illumination source such as a xenon lamp. Under atmospheric conditions, the resultant EL-PSP system reduces the temperature dependency by 54% compared to that of a conventional PSP system. An application of the EL-PSP system to a sonic jet impingement shows that the system demonstrated its reduction of the temperature dependency by 75% in a pressure measurement and reduces an image misalignment error.